Identifying 2- and 3-coordinated H2O in protonated ion–water clusters by vibrational pre-dissociation spectroscopy and ab initio calculations

Abstract

Articles you may be interested inCommunication: He-tagged vibrational spectra of the SarGlyH+ and H+(H2O)2,3 ions: Quantifying tag effects in cryogenic ion vibrational predissociation (CIVP) spectroscopy Exploring the correlation between network structure and electron binding energy in the ( H 2 O ) 7 − cluster through isomer-photoselected vibrational predissociation spectroscopy and ab initio calculations: Addressing complexity beyond types I-IIIClustering of water on protonated molecular ions has been investigated by vibrational predissociation spectroscopy. Systematic measurements at different cluster sizes reveal a close resemblance of the OH stretch spectra between NH 4 ϩ ͑H 2 O͒ n , CH 3 NH 3 ϩ ͑H 2 O͒ n , and H 3 O ϩ ͑H 2 O͒ n . Particularly at nу6, a sharp feature, identical to that found on ice and water surfaces, emerges at 3690 cm Ϫ1 for free-OH stretching. The feature is distinguished from the other free-OH absorption, commonly observed for small-and medium-sized (H 2 O) n clusters at 3715 cm Ϫ1 . The results, in conjunction with ab initio calculations, provide compelling evidence for 2-and 3-coordinated H 2 O in the protonated ion-water clusters.

Water Radical Cations in the Gas Phase: Methods and Mechanisms of Formation, Structure and Chemical Properties

“…To reveal the structures of (H 2 O) n +• at the molecular level, such as network shapes, ion core motifs and the location of the •OH radical, Mizuse carried out a systematic investigation combining IR spectroscopy, especially in the OH stretch region, and the inert gas (such as Ar) attachment technique [ 50 ]. In contrast to the case for the H + (H 2 O) n system, free OH stretch band patterns of (H 2 O) n +• were found to be quite similar to those of protonated water clusters (H 2 O) n H + (shown in Figure 28 b) reported by several groups so far [ 16 , 69 , 71 , 104 , 105 , 106 , 107 , 108 , 109 ].…”

Infrared spectroscopy of the protonated nitrogen dimer: The complexity of shared proton vibrations

“…[19][20][21][22][23] Over the past several years, new methods in selected ion infrared spectroscopy have focused on protonated clusters and especially protonbridged species, revealing the unusual dynamics that arise from proton vibrations and the varied behavior depending on the details of the shared proton potential. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] In the present study, we investigate the proton-bridged dimer of nitrogen, e.g., N 2 -H + -N 2 , using infrared spectroscopy. This deceptively simple system provides rich vibrational complexity throughout the infrared spectral region.…”

“…[19][20][21][22][23] Infrared spectroscopy in the gas phase was first reported by Lee and co-workers, [24][25][26][27][28] in studies of protonated water clusters, and other related species in the O-H stretching region. In one of the first spectroscopic studies to probe proton motions directly, Asmis et al 29 reported the infrared photodissociation spectroscopy of the proton-bridged water dimer using far-infrared radiation from the FELIX freeelectron laser.…”

Near-Infrared Spectroscopy and Anharmonic Theory of Protonated Water Clusters: Higher Elevations in the Hydrogen Bonding Landscape

“…Small protonated water clusters, H + (H 2 O) n , have been studied extensively with new experiments and theory as models for molecular proton accommodation, proton transfer intermediates, hydrogen bonding networks, and solvation. − Infrared spectroscopy of size-selected clusters has become possible with improved methods for ion cooling and manipulation with mass spectrometers, while various computational approaches have been employed to identify isomeric structures and their spectra for each cluster size. In studies to date, vibrational spectroscopy has been employed primarily in the mid-IR, where the fundamentals of free O–H stretches, hydrogen-bonded O–H stretches, and shared-proton vibrations occur.…”

“…Since the earliest spectroscopic studies, it has been recognized that protonated water clusters can form competing isomeric structures differing in their charge site and/or hydrogen-bonding connectivity. − The combined efforts of experiments and theory have been able to identify the key spectral features for these structures. The hydronium ion forms the core of many of these clusters, but the shared-proton Zundel moiety also plays a role at certain cluster sizes. ,, Special consideration has also been given to the Eigen ion, H + (H 2 O) 4 , which has a symmetrically solvated hydronium structure.…”